In vitro investigations Flashcards
What are supersomes/baculosomes and what are they used for?
Supersomes are recombinant insect cells that can express the human CYP and UGT enzymes.
These are used for human biotransformation studies.
What are human liver microsomes?
The most popular model in human drug biotransformation research
They are artificial structures derived from fragments of the human hepatocyte endoplasmatic reticulum during the tissue homogenization step.
Microsomes contain the enzymes CYP and UGT
Which enzymes can be investigated with human liver cytosol fractions?
The cytosolic enzymes:
- NAT (N-acetyl transferase)
- GST (gluthathione-s-transferase)
- ST (sulfotransferase)
What characterizes human liver S9 fraction?
It includes everything from the cells and it therefore suitable for investigations of phase 1 and 2 enzymes.
It is used for Ames test - a mutagenicity assay.
However the expression of enzymes is low.
What characterizes liver cell lines?
1) De-differentiated
2) Low expression of enzymes, varies according to the content of the culture medium
3) Transgene
Due to these factors, liver cell lines are rarely used
What characterizes hepatocytes (used in in vitro investigation)?
They are a good in vitro/vivo correlation.
Advantages of the model are:
- Well-established and characterized
- Viability for up to 4 weeks
- Study of mediators and enzyme inducers possible
- Viable cell enrichment possible
- Cryopreservation possible
- Drug transporters are still present and operational
Disadvantages of the model:
- Isolation can be complicated and time-consuming
- Only preselected cells can be studied
- Cell damage during isolation
- Cellular interactions are more difficult to study
What are the two main classes of drug transporters and which transporters do they include?
1) Efflux transporters (ABC – ATP binding casstte)
- P-gp (P-glycoprotein)
- BCRP (breast cancer resistance protein)
2) Uptake transporters (SLC – solute carriers)
- OAT (organic anion transporter)
- OCT (organic cation transporter)
- OATP (organic anion transporting polypeptides)